1. Field of the Invention
The invention relates to a carrier device which moves three axes XY.theta.. The invention relates especially to a carrier device which can be used for machinery and devices of various types, such as optical devices, measuring instruments, machine tools, screen printing machines or the like. The invention furthermore relates particularly to a carrier using a mask or silicon wafer in a semiconductor exposure device.
2. Background of the Invention
It is generally known that there is a demand for a technology for optical devices and the like in which a carrier, on which a workpiece or the like is seated, is moved in the X-Y direction and at the same time is rotated through a stipulated angle, which is hereinafter called "moving in the .theta. direction," and in which the workpiece attached to the carrier is positioned with reference to three axes XY.theta..
For example, in the production of a semiconductor device, a micro machine or the like, a process in which the carrier is positioned with reference to the XY.theta. axes, as described above, and in which the workpiece is exposed with mask patterns, or similar processes is accomplished. Often one such carrier device is conventionally formed by positions of the carriers on top of one another.
FIG. 10 illustrates a carrier device which is known as a carrier device with a carrier-positioning arrangement and a relatively small stroke as prior art. FIG. 10(a) is a schematic representation of the carrier device in an overhead view and FIG. 10(b) is a cross-sectional representation taken along the line A--A in FIG. 10(a). A device for positioning a carrier in the X-Y-.theta. direction is shown on which a mask is seated in which patterns are thermally baked.
In the representation, reference number 11 is a mask holder for holding a mask, reference number 12 is a mask, reference number 13 is a mask pattern on the mask, reference numbers 14 and 14' are orientation points for positioning purposes which are recorded on the mask, and reference number 15 is a base on which a carrier is seated. Reference number 17 designates an XY carrier which moves in direction X-Y (in FIG. 10(a), a direction to the right is called the X direction and a direction to the top is called the Y direction). X-Y carrier 17 is installed over planar guide part 28 on base 15, such that it can move in the direction of the X axis and direction of the Y axis, and is pretensioned by a tension spring 27 in the direction toward the bottom left in FIG. 10(a).
Reference number 18 indicates a .theta. carrier which is rotatably installed on X-Y carrier 17 over .theta. bearing 29, and is rotatably pretensioned in a counterclockwise direction by a compression spring 26 that is located between component 17a installed in X-Y carrier 17 and component 18a installed in .theta. carrier 18.
Reference number 21 designates an X axis drive element for moving X-Y carrier 17 in the X direction, reference number 21a indicates an X axis drive motor and reference number 21b designates a coder for determining the amount of rotation of drive motor 21a. Reference number 21c indicates a conversion device which converts rotation into linear motion. Hereinafter it is called "rotation/linear motion conversion device". Reference number 21f designates a roller which comes into contact with X-Y carrier 17, which is driven by means of X axis drive element 21 to the right and left in FIG. 10(a) and which moves the X-Y carrier 17 in the direction of the X axis.
Reference number 23 indicates a Y axis drive element for moving the X-Y carrier in the Y direction and reference numbers 23a through 23f, respectively, label the components which correspond to the like-lettered components of the above-described X axis drive element.
Reference number 25 designates a .theta. axis drive element for rotating the .theta. carrier and reference numbers 25a through 25f, respectively, indicate the components which correspond to the like-lettered components of the above-described X axis drive element.
An output of coder 21b or the like located in the respective drive element is input into a control device which consists of a computer or the like (not shown). Motor 21a or the like located in the respective drive element is driven based on the output of the above-described control device.
In addition, various means can be used for rotation/linear motion conversion device 21c or the like as a means for linearly driving roller 21f or the like. For example, with screws or cams rotary motion of the motor can be converted into linear motion, and thus, roller 21f or the like can be driven (as necessary a reducing gear can also be used) or roller 21f or the like can be driven using a linear motor. Various types of motors can be used as the motor, such as a stepping motor, a DC motor, or the like. In addition, in the case in which a drive with high accuracy is necessary, piezoelements or the like can be used.
When an operator is positioning mask 12 in a stipulated position by means of an optical device or the like (not shown). verifies positions of orientation points 14, 14' recorded on the mask 12, a reference signal is input into the above described control device, such that the above described orientation points 14, 14' agree with the stipulated positions to be achieved. After inputting of the reference signal by the operator, the control device compares a feedback signal input from decoder 21b or the like with the above described reference signal, drives motor 21a or the like, and controls one position of the X-Y carrier as well as an angle of rotation of the .theta. carrier, such that the position of the X-Y carrier and the angle of rotation of the .theta. carrier agree with the reference signal input by the operator.
The carrier device shown in FIG. 10 can drive the X-Y carrier and the .theta. carrier independently of one another by the position arrangement of the X-Y carrier and .theta. carrier. Therefore, in doing so, it is considered disadvantageous that, in spite of simple positioning of mask 12, a great height and thus a heavy weight of the carrier arise since the two carriers are placed on one another.
A device illustrated in FIG. 11 is known as a carrier device in which movement in the X-Y-.theta. direction is executed by means of a single carrier and the height and weight are reduced. FIG. 11(a) is a schematic of a carrier device in an overhead view and FIG. 11(b) is a cross section taken along line A--A in FIG. 11(a), on which a mask is seated in which patterns are thermally baked as shown as in FIG. 10.
In the representation the same parts as in FIG. 10 are provided with the same reference numbers. Carrier 16 is installed over planar guide part 28 on base 15 and by means of planar guide part 28 can be movably held in the direction of the X-Y axis and at the same time is pivotally held in the .theta. direction. In X axis drive element 21 is a drive part 21d which is driven by motor 21a to the right and left in FIG. 11(a) and can vibrate with respect to carrier 16 and is at the same time slidable.
FIG. 12 shows schematically an arrangement of the above described drive part 21d. Here, FIG. 12(a) is a cross section of drive part 21d and FIG. 12(b) is a cross section of the drive part 21d taken along line A--A in FIG. 12(A).
In the representation, reference number 30 indicates a slide rail attachment part which is installed in carrier 16 with screws or the like, reference number 31 is a slide rail which is attached in slide rail attachment part 30, reference number 32 is a linear bearing and reference number 33 is a slide bearing housing. Slide rail 31 slides by means of linear bearing 32 to the right and left in FIG. 12(a). Reference number 34 labels a drive component which is driven to the top and bottom in the representation by means of motor 21b and reference number 35 is an axis of rotation. Slide bearing housing 33 is installed with vibration capacity via bearing 36 in axis of rotation 35 which is located in drive component 34. Carrier 16 can, therefore, move to the right and left in FIG. 12(a) with reference to drive component 34 and can at the same time vibrate.
In FIG. 11, reference number 22 designates an X' axis drive element for driving carrier 16 in the direction of the X axis and reference number 23 labels a Y axis drive element for driving carrier 16 in the direction of the Y axis, and which, like the X axis drive element, is provided with drive parts 22d and 23d and is arranged to vibrate and at the same time slide relative to carrier 16.
As in the device shown in FIG. 10, after input of a reference signal into a control device by an operator, motor 21a or the like is driven, and control is executed such that one position and one angle of rotation of the carrier agree with the reference signal. In contrast to the device shown in FIG. 10, the control device drives X-axis drive element 21 and X' axis drive element 22 at the same time in the same direction by the same amount, moves carrier 16 in the direction of the X-axis, and thus, executes positioning in the direction of the X-axis. Furthermore, by driving Y-axis drive element 23, carrier 16 is moved in the direction of the Y axis, and thus, positioning in the direction of the Y axis is done. Furthermore, the above described X-axis drive element 21, X' axis drive element 22 and Y-axis drive element 23 are simultaneously driven in a direction in which the carrier is turned around reference axis R through a necessary angle, and thus, positioning in the .theta. direction is obtained.
FIG. 13 shows schematically the above described movement of the carrier with FIG. 13 (a) showing reference axis R which acts as an action point and center of rotation of the respective drive element (in this example one position of orientation point 14' is designated the reference axis) and FIG. 13(b) showing the respective mount of movement of the orientation point by the respective drive element when the carrier moves in the X-Y-.theta. direction.
First, X axis movement is accomplished. As is shown in the drawing, X axis drive element 21 and X' axis drive element 22 are driven in the same direction by the same amount, action points A and B are each moved by a and the positions of the orientation points 14, 14' on mask 12 are moved in the direction of the X axis by a. In this way the position of orientation point 14a in the X direction agrees with one position of point W14' recorded on the workpiece in the X direction.
Next Y axis movement is effected. Y axis drive element 23 is driven in the Y axis direction, one action point C is moved by b and the position of orientation point 14' is moved in the direction of the Y axis by b. In this way the position of orientation point 14' agrees with the position of point W14' recorded on the workpiece.
Next .theta. axis movement is effected. Orientation point 14 is turned around reference axis R by .theta.. This means that in order to prevent movement of the position of reference axis R, X axis drive element 21 is driven to the left, and thus, action point A is moved by c, X' axis drive element 22 is driven to the right, and thus, action point B is moved by d, and the Y axis drive element 23 is driven downward and action point C is moved by e.
Orientation points 14, 14' agree in this way with alignment mark points W14, W14' recorded on the workpiece. In this case, when the carrier turns relative to the reference axis by .theta. the respective amounts c, d and e in which X axis drive element 21, X' axis drive element 22 and Y axis drive element 23 are driven, are not always identical to one another, as is apparent from FIG. 13. When carrier 16 turns, it is therefore necessary to compute the respective amount of drive c, d and e of the respective drive dement.
As described above, in the carrier device shown in FIG. 10 it is considered disadvantageous that as the result of the position arrangement of the X-Y carrier and .theta. carrier in spite of simple positioning, a complicated arrangement and at the same time a great height and heavy weight arise. In the device shown in FIG. 10, therefore, in addition to the complicated arrangement, the disadvantages of a large drive device and high cost arose, since the speed of positioning cannot be raised without increasing the output power of the respective drive element. In addition, here, it was considered disadvantageous that, due to the carriers placed in two stages, one on the other, a great height arises, and that, for this reason, the accuracy of movement and vibration resistance are impaired.
On the other hand, in the carrier device illustrated in FIG. 11, there is no serious disadvantage with respect to efficiency, since here the weight is relatively light and the height is small, and since the output power of the respective drive element need not be increased as much as in the carrier device shown in FIG. 10. However, here, it was considered disadvantageous that, as the result of a different drive stroke of the respective drive element When the carrier turns, control is difficult, and that the control device is heavily loaded.
Furthermore, in the carrier devices shown in FIGS. 10 and 11, the disadvantage arose that, when used in an environment in which a temperature rise/temperature drop occurs, due to thermal expansion, the position of the reference point changes, and thus, control accuracy decreases. In particular, when using the above described carrier devices for a semiconductor exposure device, thermal expansion of the carriers occurs due to irradiation of the carriers with light during exposure.
For example, in the carrier devices shown in FIGS. 11 and 13 when the temperature rises, reference axis R moves with respect to action points A and B, which forces the position of carrier 16 to the right in the representation. Furthermore,. the reference axis R moves upward with respect to action point C, and thus, the position of reference axis R changes.